Preparation And Tribological Properties Of Ce(Eu)-1,10-Phenanthroline-Oleic Acid/Graphene Composites

Rare earth elements are widely used in many fields due to their unique 4f electronic structure and physical and chemical properties.In the field of lubrication,it has been proved that the introduction of rare earth compounds can greatly improve the hold-bearing capacity and wear resistance of lubricating oil or solid lubricating film.However,as a kind of additive of lubricating oil,the dispersity of rare earth in lubricating oil has become an urgent problem to be solved.The unique layered structure and low shear force of educed graphene oxide?RGO?make it an ideal lubricating material.However,due to the existence of van der Waals force between layers,RGO layers are easy to agglomerate,which hinders the practical application.Rare earth organic complex is an oil soluble extreme pressure antiwear additive with excellent properties.As a common ligand,unique large?-conjugated structure of 1,10-phenanthroline?Phen?contributes to the adsorption on friction interface.Additionally,the longer carbon chain structure and weaker polarity of oleic acid?OA?are similar to those of base oil.Therefore,oleic acid is selected as the second ligand on the principle of the dissolution in the similar material structure.Then,it was compounded with RGO to study the structure design and tribological properties of rare earth organic complex composite.The main research contents are as follows:1.Ce?Phen??OA?₃,an organic ternary complex,was prepared by one pot method.The composition and structure of the complex were characterized by FTIR,UV,NMR and TGA.The tribological properties of lubricating oil with different concentrations of target products were investigated by SRV-?fretting friction and wear tester.It is found that the dispersion stability of Ce?Phen??OA?₃ in base oil is improved,and the life of base oil is extended.A small amount?0.1%?of Ce?Phen??OA?₃ could improve the extreme pressure by 67%,and the wear volume/wear rate decreased by 98%2.Eu?Phen??OA?₃ was prepared by one pot method.The results show that the structures of Eu?Phen??OA?₃ and Ce?Phen??OA?₃ are similar.The life of base oil with Eu?Phen??OA?₃ is longer than that with Ce?Phen??OA?₃.A very small amount of Eu?Phen??OA?₃?0.06%?is able to increase the extreme pressure by 150%compared with the base oil and the wear volume with Eu?Phen??OA?₃ is 93%lower than that with Ce?Phen??OA?₃.In addition,the wear volume with Eu?Phen??OA?₃ accounts for about24%of that with Ce?Phen??OA?₃.3.RGO/Eu?Phen??OA?₃?RGECs?composites were successfully synthesized by simple hydrothermal method.The ratio of precursor of GO colloidal suspension can be adjusted at the same time.RGECs not only contains the lubricity of graphene,but also has excellent wear resistance of that of Eu?Phen??OA?₃.In particular,Eu?Phen??OA?₃can not only resist wear,but also play a role in isolation and prevent graphene nanosheets from re-stacking.In the same way,graphene nanosheets provide a good support for Eu?Phen??OA?₃,and the prepared RGECs have good dispersion stability in the base oil.The friction coefficient has no obvious change,however,the service life of the base oil is greatly improved,which is better than the commercial additive ZDDP.At the same time,adding appropriate amount?0.08%?of RGECs can reduce the wear spot area by about 56%,the wear volume/wear rate by about 37%compared with ZDDP,which indicates that the wear resistance is enhanced.